1,3-disubstituted-4-phenyl-1H-pyridin-2-ones

ABSTRACT

The present invention relates to novel compounds, in particular novel pyridinone derivatives according to Formula (I) 
                         
wherein all radicals are as defined in the application and claims. The compounds according to the invention are positive allosteric modulators of metabotropic receptors—subtype 2 (“mGluR2”) which are useful for the treatment or prevention of neurological and psychiatric disorders associated with glutamate dysfunction and diseases in which the mGluR2 subtype of metabotropic receptors is involved. In particular, such diseases are central nervous system disorders selected from the group of anxiety, schizophrenia, migraine, depression, and epilepsy. The invention is also directed to pharmaceutical compositions and processes to prepare such compounds and compositions, as well as to the use of such compounds for the prevention and treatment of such diseases in which mGluR2 is involved.

IN THE CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Application No. 07116391.9, filed Sep. 14, 2007, which is hereby incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to novel pyridinone-derivatives which are positive allosteric modulators, of the metabotropic glutamate receptor subtype 2 (“mGluR2”) and which are useful for the treatment or prevention of neurological and psychiatric disorders associated with glutamate dysfunction and diseases in which the mGluR2 subtype of metabotropic receptors is involved. The invention is also directed to pharmaceutical compositions comprising such compounds, to processes to prepare such compounds and compositions, and to the use of such compounds for the prevention or treatment of neurological and psychiatric disorders and diseases in which mGluR2 is involved.

BACKGROUND OF THE INVENTION

Glutamate is the major amino acid neurotransmitter in the mammalian central nervous system. Glutamate plays a major role in numerous physiological functions, such as learning and memory but also sensory perception, development of synaptic plasticity, motor control, respiration, and regulation of cardiovascular function. Furthermore, glutamate is at the centre of several different neurological and psychiatric diseases, where there is an imbalance in glutamatergic neurotransmission.

Glutamate mediates synaptic neurotransmission through the activation of ionotropic glutamate receptors channels (iGluRs), and the NMDA, AMPA and kainate receptors which are responsible for fast excitatory transmission.

In addition, glutamate activates metabotropic glutamate receptors (mGluRs) which have a more modulatory role that contributes to the fine-tuning of synaptic efficacy.

Glutamate activates the mGluRs through binding to the large extracellular amino-terminal domain of the receptor, herein called the orthosteric binding site. This binding induces a conformational change in the receptor which results in the activation of the G-protein and intracellular signaling pathways.

The mGluR2 subtype is negatively coupled to adenylate cyclase via activation of Gαi-protein, and its activation leads to inhibition of glutamate release in the synapse. In the central nervous system (CNS), mGluR2 receptors are abundant mainly throughout cortex, thalamic regions, accessory olfactory bulb, hippocampus, amygdala, caudate-putamen and nucleus accumbens.

Activating mGluR2 was shown in clinical trials to be efficacious to treat anxiety disorders. In addition, activating mGluR2 in various animal models was shown to be efficacious, thus representing a potential novel therapeutic approach for the treatment of schizophrenia, epilepsy, addiction/drug dependence, Parkinson's disease, pain, sleep disorders and Huntington's disease.

To date, most of the available pharmacological tools targeting mGluRs are orthosteric ligands which activate several members of the family as they are structural analogs of glutamate.

A new avenue for developing selective compounds acting at mGluRs is to identify compounds that act through allosteric mechanisms, modulating the receptor by binding to a site different from the highly conserved orthosteric binding site.

Positive allosteric modulators of mGluRs have emerged recently as novel pharmacological entities offering this attractive alternative. Various compounds have been described as mGluR2 positive allosteric modulators. WO2004/092135 (NPS & Astra Zeneca), WO2004/018386, WO2006/014918 and WO2006/015158 (Merck), WO2001/56990 (Eli Lilly) and WO2006/030032 (Addex & Janssen Pharmaceutica) describe respectively phenyl sulfonamide, acetophenone, indanone, pyridylmethyl sulfonamide and pyridinone derivatives as mGluR2 positive allosteric modulators. None of the specifically disclosed compounds therein are structurally related to the compounds of the present invention.

It was demonstrated that such compounds do not activate the receptor by themselves. Rather, they enable the receptor to produce a maximal response to a concentration of glutamate which by itself induces a minimal response. Mutational analysis has demonstrated unequivocally that the binding of mGluR2 positive allosteric modulators does not occur at the orthosteric site, but instead at an allosteric site situated within the seven transmembrane region of the receptor.

Animal data are suggesting that positive allosteric modulators of mGluR2 have effects in anxiety and psychosis models similar to those obtained with orthosteric agonists. Allosteric modulators of mGluR2 were shown to be active in fear-potentiated startle, and in stress-induced hyperthermia models of anxiety. Furthermore, such compounds were shown to be active in reversal of ketamine- or amphetamine-induced hyperlocomotion, and in reversal of amphetamine-induced disruption of prepulse inhibition of the acoustic startle effect models of schizophrenia (J. Pharmacol. Exp. Ther. 2006, 318, 173-185; Psychopharmacology 2005, 179, 271-283).

Recent animal studies further reveal that the selective positive allosteric modulator of metabotropic glutamate receptor subtype 2 biphenyl-indanone (BINA) blocks a hallucinogenic drug model of psychosis, supporting the strategy of targeting mGluR2 receptors for treating glutamatergic dysfunction in schizophrenia (Mol. Pharmacol. 2007, 72, 477-484).

Positive allosteric modulators enable potentiation of the glutamate response, but they have also been shown to potentiate the response to orthosteric mGluR2 agonists such as LY379268 or DCG-IV. These data provide evidence for yet another novel therapeutic approach to treat above mentioned neurological and psychiatric diseases involving mGluR2, which would use a combination of a positive allosteric modulator of mGluR2 together with an orthosteric agonist of mGluR2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to compounds having metabotropic glutamate receptor 2 modulator activity, said compounds having the Formula (I)

and the stereochemically isomeric forms thereof, wherein

-   R¹ is C₁₋₆alkyl; or C₁₋₃alkyl substituted with C₃₋₇cycloalkyl,     phenyl, or phenyl substituted with halo, trifluoromethyl or     trifluoromethoxy; -   R² is halo, trifluoromethyl, C₁₋₃alkyl or cyclopropyl; -   R³ is hydrogen, halo or trifluoromethyl; -   R⁴ is hydrogen, C₁₋₃alkyl, C₁₋₃alkyloxy, hydroxyC₁₋₃alkyl or     tetrahydropyran-2-yloxyC₁₋₃alkyl; -   n is 1 or 2; -   X is a covalent bond, O or NR⁵; -   R⁵ is hydrogen, C₁₋₃alkyl or hydroxyC₂₋₃alkyl; -   Y is O or CR⁶(OH); -   R⁶ is hydrogen or C₁₋₃alkyl; or -   R⁴ and R⁶ form a radical —CH₂—CH₂—;     and the pharmaceutically acceptable salts and solvates thereof.     In one embodiment, the invention relates to a compound according to     Formula (I) or a stereochemically isomeric form thereof, wherein -   R¹ is 1-butyl, 2-methyl-1-propyl, 3-methyl-1-butyl,     (cyclopropyl)methyl or 2-(cyclopropyl)-1-ethyl; -   R² is chloro, bromo, cyclopropyl or trifluoromethyl; -   R³ is hydrogen, chloro or trifluoromethyl; -   R⁴ is hydrogen or hydroxymethyl; -   n is 2; -   X is a covalent bond, O or NR⁵; -   R⁵ is hydrogen; -   Y is O or CR⁶(OH); -   R⁶ is hydrogen or methyl;     or a pharmaceutically acceptable salt or solvate thereof.     In one embodiment, the invention relates to a compound according to     Formula (I) or a stereochemically isomeric form thereof, wherein -   R¹ is 1-butyl, 3-methyl-1-butyl, (cyclopropyl)methyl or     2-(cyclopropyl)-1-ethyl; -   R² is chloro; -   R³ is hydrogen or chloro; -   R⁴ is hydrogen or hydroxymethyl; -   n is 2; -   X is a covalent bond, O or NR⁵; -   R⁵ is hydrogen; -   Y is O or CR⁶(OH); -   R⁶ is hydrogen or methyl;     or a pharmaceutically acceptable salt or solvate thereof.

The notation C₁₋₃alkyl as a group or part of a group defines a saturated, straight or branched, hydrocarbon radical having from 1 to 3 carbon atoms, such as methyl, ethyl, 1-propyl and 1-methylethyl.

The notation C₁₋₆alkyl as a group or part of a group defines a saturated, straight or branched, hydrocarbon radical having from 1 to 6 carbon atoms such as methyl, ethyl, 1-propyl, 1-methylethyl, 1-butyl, 2-methyl-1-propyl, 3-methyl-1-butyl, 1-pentyl, 1-hexyl and the like. The notation —(CH₂)_(n)— is abbreviated C_(n) in the formulae.

The notation C₃₋₇cycloalkyl defines a saturated, cyclic hydrocarbon radical having from 3 to 7 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl.

The notation halo or halogen as a group or part of a group is generic for fluoro, chloro, bromo, iodo.

For therapeutic use, salts of the compounds of formula (I) are those wherein the counterion is pharmaceutically acceptable. However, salts of acids and bases which are non-pharmaceutically acceptable may also find use, for example, in the preparation or purification of a pharmaceutically acceptable compound. All salts, whether pharmaceutically acceptable or not, are included within the ambit of the present invention.

The pharmaceutically acceptable salts are defined to comprise the therapeutically active non-toxic acid addition salt forms that the compounds according to Formula (I) are able to form. Said salts can be obtained by treating the base form of the compounds according to Formula (I) with appropriate acids, for example inorganic acids, for example hydrohalic acid, in particular hydrochloric acid, hydrobromic acid, sulphuric acid, nitric acid and phosphoric acid; organic acids, for example acetic acid, hydroxyacetic acid, propanoic acid, lactic acid, pyruvic acid, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, cyclamic acid, salicylic acid, p-aminosalicylic acid and pamoic acid.

Conversely said salt forms can be converted into the free base form by treatment with an appropriate base.

The compounds according to Formula (I) containing acidic protons may also be converted into their therapeutically active non-toxic base salt forms by treatment with appropriate organic and inorganic bases. Appropriate base salt forms comprise, for example, the ammonium salts, the alkaline and earth alkaline metal salts, in particular lithium, sodium, potassium, magnesium and calcium salts, salts with organic bases, e.g. the benzathine, N-methyl-D-glucamine, hybramine salts, and salts with amino acids, for example arginine and lysine.

Conversely, said salt forms can be converted into the free acid forms by treatment with an appropriate acid.

The term solvate comprises the solvent addition forms as well as the salts thereof, which the compounds of formula (I) are able to form. Examples of such solvent addition forms are e.g. hydrates, alcoholates and the like.

The term “stereochemically isomeric forms” as used hereinbefore defines all the possible isomeric forms that the compounds of Formula (I) may possess. Unless otherwise mentioned or indicated, the chemical designation of compounds denotes the mixture of all possible stereochemically isomeric forms, said mixtures containing all diastereomers and enantiomers of the basic molecular structure. The invention also embraces each of the individual isomeric forms of the compounds of Formula (I) and their salts and solvates, substantially free, i.e. associated with less than 10%, preferably less than 5%, in particular less than 2% and most preferably less than 1% of the other isomers. Thus, when a compound of formula (I) is for instance specified as (R), this means that the compound is substantially free of the (S) isomer. Stereogenic centers may have the R- or S-configuration; substituents on bivalent cyclic (partially) saturated radicals may have either the cis- or trans-configuration.

Following CAS nomenclature conventions, when two stereogenic centers of known absolute configuration are present in a compound, an R or S descriptor is assigned (based on Cahn-Ingold-Prelog sequence rule) to the lowest-numbered chiral center, the reference center. The configuration of the second stereogenic center is indicated using relative descriptors [R*,R*] or [R*,S*], where R* is always specified as the reference center and [R*,R*] indicates centers with the same chirality and [R*,S*] indicates centers of unlike chirality. For example, if the lowest-numbered chiral center in the compound has an S configuration and the second center is R, the stereo descriptor would be specified as S—[R*,S*]. If “α” and “β” are used: the position of the highest priority substituent on the asymmetric carbon atom in the ring system having the lowest ring number, is arbitrarily always in the “α” position of the mean plane determined by the ring system. The position of the highest priority substituent on the other asymmetric carbon atom in the ring system (hydrogen atom in compounds according to Formula (I)) relative to the position of the highest priority substituent on the reference atom is denominated “α”, if it is on the same side of the mean plane determined by the ring system, or “β”, if it is on the other side of the mean plane determined by the ring system.

In the framework of this application, an element, in particular when mentioned in relation to a compound according to Formula (I), comprises all isotopes and isotopic mixtures of this element, either naturally occurring or synthetically produced, either with natural abundance or in an isotopically enriched form. Radio labelled compounds of Formula (I) may comprise a radioactive isotope selected from the group of ³H, ¹¹C, ¹⁸F, ¹²²I, ¹²³I, ¹²⁵I, ¹³¹I, ⁷⁵Br, ⁷⁶Br, ⁷⁷Br and ⁸²Br. Preferably, the radioactive isotope is selected from the group of ³H, ¹¹C and ¹⁸F.

Preparation

The compounds according to the invention can generally be prepared by a succession of steps, each of which is known to the skilled person. In particular, the compounds can be prepared according to the following synthesis methods.

The compounds of Formula (I) may be synthesized in the form of racemic mixtures of enantiomers which can be separated from one another following art-known resolution procedures. The racemic compounds of Formula (I) may be converted into the corresponding diastereomeric salt forms by reaction with a suitable chiral acid. Said diastereomeric salt forms are subsequently separated, for example, by selective or fractional crystallization and the enantiomers are liberated therefrom by alkali. An alternative manner of separating the enantiomeric forms of the compounds of Formula (I) involves liquid chromatography using a chiral stationary phase. Said pure stereochemically isomeric forms may also be derived from the corresponding pure stereochemically isomeric forms of the appropriate starting materials, provided that the reaction occurs stereospecifically.

A. Preparation of the Final Compounds Experimental Procedure 1

The compounds according to Formula (I) can be prepared by reacting an intermediate of Formula (II) with an intermediate of Formula (III) according to reaction scheme (1), a reaction that is performed in a suitable reaction-inert solvent, such as, for example, 1,4-dioxane or mixtures of inert solvents such as, for example, 1,4-dioxane/DMF, in the presence of a suitable base, such as, for example, aqueous NaHCO₃ or Na₂CO₃, a Pd-complex catalyst such as, for example, tetrakis(triphenylphosphine)palladium(0), heating for a suitable period of time that allows the completion of the reaction either under traditional heating or under microwave irradiation. W is a group suitable for Pd mediated coupling with boronic acids or boronic esters, such as, for example, a halogen or triflate and R⁵ and R⁶ may be hydrogen or alkyl, or may be taken together to form for example the bivalent radical of formula —CH₂CH₂—, —CH₂CH₂CH₂—, or —C(CH₃)₂C(CH₃)₂—. In reaction scheme (1), all other variables are defined as in Formula (I).

Experimental Procedure 2

Alternatively, compounds according to Formula (I), in the case of R² being halogen, can be prepared by reacting an intermediate of Formula (IV) with a N-halosuccinimide reagent such as, for example, N-chlorosuccinimide, N-bromosuccinimide or N-iodosuccinimide, according to reaction scheme (2). This reaction is performed in a suitable reaction-inert and aprotic solvent, such as, for example, dichloromethane or dimethylformamide, stirring the reaction mixture at a suitable temperature and for the required time to achieve completion of the reaction. In reaction scheme (2), all other variables are defined as in Formula (I).

Such intermediates (II), (III) and (IV) may be prepared according to reaction schemes (3) to (21) (see below). The transformations of different functional groups, present in the final compounds or in the intermediates, into other functional groups according to Formula (I) can be performed by synthesis methods well known by the person skilled in the art.

B. Preparation of the Intermediate Compounds Experimental Procedure 3

Intermediates of Formula (II-a) can be prepared by reacting an intermediate of Formula (V) with a suitable halogenating agent such as, for example, phosphorus oxybromide, a reaction that is performed in a suitable reaction-inert solvent such as, for example, DMF, at a moderately elevated temperature such as, for example, 110° C. In reaction scheme (3), all variables are defined as in Formula (I).

Experimental Procedure 4

Intermediates of Formula (II-b) can be prepared by reacting an intermediate of Formula (V) with triflic anhydride (also called trifloromethanesulfonic anhydride), a reaction that is performed in a suitable reaction-inert solvent such as, for example, dichloromethane, in the presence of a base such as, for example, pyridine at a low temperature such as, for example, −78° C. In reaction scheme (4), all variables are defined as in Formula (I).

Experimental Procedure 5

Intermediates of Formula (V-a) (wherein R² is halo), can be prepared by reacting an intermediate of Formula (VI) with a N-halosuccinimide reagent, such as N-chlorosuccinimide, N-bromosuccinimide or N-iodosuccinimide, according to reaction scheme (5). This reaction is performed in a suitable reaction-inert and aprotic solvent, such as, for example, dichloromethane or 1,2-dichloroethane, stirring the reaction mixture at a suitable temperature, typically at room temperature, for the required time to achieve completion of the reaction. In reaction scheme (5), variable R¹ is defined as in Formula (I).

Experimental Procedure 6

Intermediates of Formula (V-b) (wherein R²=trifluoromethyl, C₁₋₃alkyl or cyclopropyl), can be prepared by hydrogenation of intermediates of Formula (VII), in a suitable reaction-inert solvent such as, for example, ethanol, in the presence of a catalyst such as, for example, 10% palladium on activated carbon, for a period of time that ensures the completion of the reaction, typically at room temperature and 1 atmosphere of hydrogen for 2 hours. In reaction scheme (6), variable R¹ is defined as in Formula (I).

Experimental Procedure 7

Intermediates of Formula (VI) can be prepared by hydrogenolysis of intermediates of Formula (VIII), in a suitable reaction-inert solvent such as, for example, ethanol, in the presence of a catalyst such as, for example, 10% palladium on activated carbon, for a period of time that ensures the completion of the reaction, typically at room temperature and 1 atmosphere of hydrogen for 2 hours. In reaction scheme (7), variable R¹ is defined as in Formula (I).

Experimental Procedure 8

Intermediates of Formula (VIII) can be prepared by art known procedures by reacting commercially available 4-benzyloxy-1H-pyridin-2-one with a commercially available alkylating agent of Formula (IX), in which Z is a suitable leaving group, using a base such as, for example, K₂CO₃, and, optionally an iodine salt such as, for example, KI, in an inert solvent such as, for example, acetonitrile or DMF, at a moderately high temperature such as, for example, 80-120° C., for a suitable period of time that allows the completion of the reaction, for example 16 hours. In reaction scheme (8), variable R¹ is defined as in Formula (I) and Z is a suitable leaving group such as, for example, halogen.

Experimental Procedure 9

Intermediates of Formula (VII-a) can be prepared by reacting an intermediate of Formula (X) with a commercially available N-halosuccinimide, such as N-chloro- (NCS), N-bromo- (NBS) or N-iodosuccinimide (NIS), in a suitable reaction-inert solvent such as, for example, DMF, dichloromethane or acetic acid, typically at room temperature for 1 to 24 hours. In reaction scheme (9), variable R¹ is defined as in Formula (I).

Experimental Procedure 10

Intermediates of Formula (VII-b) can be prepared by reacting an intermediate of Formula (VII-a), wherein Halo is iodine, with commercially available methyl 2,2-difluoro-2-(fluorosulfonyl)acetate, in a suitable reaction-inert solvent such as, for example, DMF, in presence of a suitable copper salt such as copper(I) iodide, heating for a suitable period of time that allows the completion of the reaction, for example at 100° C. for 5 hours. In reaction scheme (10), variable R¹ is defined as in Formula (I).

Experimental Procedure 11

Intermediates of Formula (VII-c) can be prepared by reacting an intermediate of Formula (VII-a) with a C₁₋₃alkyl- or cyclopropyl-boronic acid derivative such as, for example, cyclopropylboronic acid or methylboronic acid, in a suitable reaction-inert solvent such as, for example, 1,4-dioxane, in the presence of a suitable palladium catalyst-complex such as, for example, [1,1′-bis(diphenylphosphino)-ferrocene]-dichloropalladium(II)—DCM complex, and in the presence of a suitable base such as NaHCO₃ heating for a suitable period of time that allows the completion of the reaction, for example at 175° C. for 20 minutes under microwave irradiation. In reaction scheme (11), variable R¹ is defined as in Formula (I).

Experimental Procedure 12

Intermediates of Formula (III) can be prepared by art known procedures by reacting an intermediate of Formula (XI) with a suitable boron source such as, for example, bis(pinacolato)diboron in the presence of a palladium catalyst such as, for example, 1,1″-bis(diphenylphosphino)ferrocenepalladium(II)dichloride in a inert solvent such as, for example, dichloromethane, in the presence of a suitable salt such as, for example, potassium acetate at moderately high temperature such as, for example, 110° C. for as for example 16 hours.

Additionally, intermediates of Formula (III) can be prepared by art known procedures of metal-halogen exchange and subsequent reaction with an appropriate boron source from intermediates of Formula (XI). Thus, for example reaction of an intermediate of Formula (XI) with an organo lithium compound such as, for example, n-butyllithium at a moderately low temperature such as, for example, −40° C. in an inert solvent such as, for example, THF followed by subsequent reaction with an appropriate boron source such as, for example, trimethoxyborane. In reaction scheme (12), all variables are defined as in Formula (I) and R⁵ and R⁶ may be hydrogen or alkyl, or may be taken together to form for example the bivalent radical of formula —CH₂CH₂—, —CH₂CH₂CH₂—, or —C(CH₃)₂C(CH₃)₂—.

Experimental Procedure 13

Additionally, intermedates of Formula (III-a) can be prepared by reacting the commercially available intermediate of Formula (XII) with a cyclic ketone derivative of Formula (XIII) under reductive amination conditions that are known by those skilled in the art, such as for example, in the presence of triacetoxy borohydride in a suitable reaction-inert solvent, such as for example 1,2-dichloroethane, at a suitable temperature, typically room temperature, for a suitable period of time that allows the completion of the reaction.

Experimental Procedure 14

Intermediates according to Formula (IV) can be prepared by reacting an intermediate of Formula (II-a), in which R²═H, with an intermediate of Formula (III) according to reaction scheme (14). This reaction may be performed in a suitable reaction-inert solvent such as, for example, 1,4-dioxane or mixtures of inert solvents such as, for example, 1,4-dioxane/DMF. The reaction may be performed in the presence of a suitable base such as, for example, aqueous NaHCO₃ or Na₂CO₃, a Pd-complex catalyst such as, for example, tetrakis(triphenylphosphine)palladium(0), heating for a suitable period of time that allows the completion of the reaction either under traditional heating or under microwave irradiation. In reaction scheme (14), all variables are defined as in Formula (I). W is a group suitable for Pd mediated coupling with boronic acids or boronic esters, such as, for example, a halogen or triflate and R⁵ and R⁶ may be hydrogen or alkyl or may be taken together to form for example the bivalent radical of formula —CH₂CH₂—, —CH₂CH₂CH₂—, or —C(CH₃)₂C(CH₃)₂—.

Experimental Procedure 15

Intermediates of Formula (XI-a) can be prepared by art known procedures by reacting an aniline intermediate of Formula (XIV-a) with a cyclic ketone derivative of Formula (XIII), under reductive amination conditions that are known by those skilled in the art, such as for example, in the presence of triacetoxy borohydride in a suitable reaction-inert solvent, such as for example 1,2-dichloroethane, at a suitable temperature, typically room temperature, for a suitable period of time that allows the completion of the reaction. In reaction scheme (15), all variables are defined as in Formula (I) and halo- may be chloro-, bromo- or iodo-.

Experimental Procedure 16

Intermediates of Formula (XI-b) can be prepared by art known procedures by reacting a a phenol intermediate of Formula (XIV-b) with a cyclic alcohol of Formula (XV), in the presence of a phosphine, such as for example triphenylphosphine and a suitable coupling agent for Mitsunobu-like couplings, such as for example di-tert-butyl azadicarboxylate in a inert solvent such as, for example, dichloromethane, at moderately low temperature such as, for example, 25° C. for as for example 2 hours. In reaction scheme (16), all variables are defined as in Formula (I) and halo- may be chloro-, bromo- or iodo-.

Experimental Procedure 17

Additionally, intermediates of Formula (XI-c) can be prepared by art known procedures of metal-halogen exchange from intermediates of Formula (XIV-c) and subsequent reaction with a cyclic ketone of Formula (XIII). Thus for example reaction of an intermediate of Formula (XI-c) with an organo lithium compound such as, for example, n-butyllithium at a moderately low temperature such as, for example, −40° C. in an inert solvent such as, for example, THF followed by subsequent reaction with tetrahydro-4H-pyran-4-one. In reaction scheme (17), all variables are defined as in Formula (I) and halo- may be chloro-, bromo- or iodo-.

Experimental Procedure 18

Additionally, intermediates of Formula (XI-d) can be prepared by art known procedures in a two step sequence consisting in a dehydratation reaction followed by hydrogenation reaction from intermediates of Formula (XI-c). Thus for example reaction of an intermediate of Formula (XI-c) with an acid such as, for example, p-toluenesulfonic acid monohydrate at a moderately high temperature such as, for example, 100° C. in an inert solvent such as, for example, toluene for as for example 2 h, yields an intermediate of Formula (XI-e). Then, this intermediate can be hydrogenated in the presence of a catalytic amount of suitable catalyst such as for example platinum oxide in an solvent such as for example ethanol to yield intermediate (XI-d). In reaction scheme (18) halo- may be chloro-, bromo- or iodo-. All other variables are defined as in Formula (I).

Experimental Procedure 19

Additionally, intermediates of Formula (XI-0 can be prepared by art known procedures from commercially available or synthetically accessible (4-halophenyl)-acetic acid alkylester derivatives, in a two step sequence consisting in an alkylation reaction with an appropriate di-halo-derivative followed by reduction of the ester functional group to alcohol. Thus for example reaction with 2-chloroethyl ether in presence of a base, such as sodium hydride, in an inert solvent such as DMF, at the appropriate temperature and for the period of time required to ensure the completion of the reaction, typically at room temperature for 10-16 hours, yields an intermediate of formula (XI-g). Then, this intermediate can be reacted with a metal reducing reagent, such as for example lithium aluminium hydride, in an inert solvent such as tetrahydrofuran, at the appropriate temperature and for the period of time required to ensure the completion of the reaction, typically −10° C. to room temperature for 2 hours, to yield an intermediate of Formula (XI-f). In reaction scheme (19), all variables are defined as in Formula (I) and halo- may be chloro-, bromo- or iodo-.

Experimental Procedure 20

Additionally, intermediates of Formula (XI) can be prepared by art known procedures from aniline-like intermediates of Formula (XVI) via a Sandmeyer type reaction. In reaction scheme (20), all variables are defined as in Formula (I) and halo- may be chloro-, bromo- or iodo-.

Experimental Procedure 21

Intermediates of Formula (XVI) can be prepared by art known procedures from intermediates of Formula (XVII) via reduction of the nitro group to the amino function by art known procedures such as catalytic hydrogenation or the use of tin(II) chloride dihydrate as a reducting agent. In reaction scheme (21), all variables are defined as in Formula (I).

Experimental Procedure 22

Intermediates of Formula (XVII) can be prepared by art known procedures by reacting an intermediate of Formula (XVIII) with a suitable intermediate of Formula (XIX), in the presence of a suitable base such as, for example, cesium carbonate in an inert solvent such as, for example, dimethylformamide or acetonitrile, at a convenient temperature and for a suitable period of time to ensure completion of the reaction. In reaction scheme (22) all variables are defined as in Formula (I).

The starting materials according to Formulas (IX), (XIII), (XIV-a, -b and -c), (XV), (XVIII) and (XIX) are intermediates that are either commercially available or may be prepared according to conventional reaction procedures generally known by those skilled in the art.

Pharmacology

The compounds provided in this invention are positive allosteric modulators of metabotropic glutamate receptors, in particular they are positive allosteric modulators of mGluR2. The compounds of the present invention do not appear to bind to the glutamate recognition site, the orthosteric ligand site, but instead to an allosteric site within the seven transmembrane region of the receptor. In the presence of glutamate or an agonist of mGluR2, the compounds of this invention increase the mGluR2 response. The compounds provided in this invention are expected to have their effect at mGluR2 by virtue of their ability to increase the response of such receptors to glutamate or mGluR2 agonists, enhancing the response of the receptor. Hence, the present invention relates to a compound according to the present invention for use as a medicine, as well as to the use of a compound according to the invention or a pharmaceutical composition according to the invention for the manufacture of a medicament for treating or preventing, in particular treating, a condition in a mammal, including a human, the treatment or prevention of which is affected or facilitated by the neuromodulatory effect of allosteric modulators of mGluR2, in particular positive allosteric modulators thereof. The present invention also relates to a compound according to the present invention or a pharmaceutical composition according to the invention for use in the manufacture of a medicament for treating or preventing, in particular treating, a condition in a mammal, including a human, the treatment or prevention of which is affected or facilitated by the neuromodulatory effect of allosteric modulators of mGluR2, in particular positive allosteric modulators thereof. The present invention also relates to a compound according to the present invention or a pharmaceutical composition according to the invention for treating or preventing, in particular treating, a condition in a mammal, including a human, the treatment or prevention of which is affected or facilitated by the neuromodulatory effect of allosteric modulators of mGluR2, in particular positive allosteric modulators thereof.

Also, the present invention relates to the use of a compound according to the invention or a pharmaceutical composition according to the invention for the manufacture of a medicament for treating, preventing, ameliorating, controlling or reducing the risk of various neurological and psychiatric disorders associated with glutamate dysfunction in a mammal, including a human, the treatment or prevention of which is affected or facilitated by the neuromodulatory effect of positive allosteric modulators of mGluR2.

Where the invention is said to relate to the use of a compound or composition according to the invention for the manufacture of a medicament for e.g. the treatment of a mammal, it is understood that such use is to be interpreted in certain jurisdictions as a method of e.g. treatment of a mammal, comprising administering to a mammal in need of such e.g. treatment, an effective amount of a compound or composition according to the invention.

In particular, the neurological and psychiatric disorders associated with glutamate dysfunction, include one or more of the following conditions or diseases: acute neurological and psychiatric disorders such as, for example, cerebral deficits subsequent to cardiac bypass surgery and grafting, stroke, cerebral ischemia, spinal cord trauma, head trauma, perinatal hypoxia, cardiac arrest, hypoglycemic neuronal damage, dementia (including AIDS-induced dementia), Alzheimer's disease, Huntington's Chorea, amyotrophic lateral sclerosis, ocular damage, retinopathy, cognitive disorders, idiopathic and drug-induced Parkinson's disease, muscular spasms and disorders associated with muscular spasticity including tremors, epilepsy, convulsions, migraine (including migraine headache), urinary incontinence, substance tolerance, substance withdrawal (including substances such as, for example, opiates, nicotine, tobacco products, alcohol, benzodiazepines, cocaine, sedatives, hypnotics, etc.), psychosis, schizophrenia, anxiety (including generalized anxiety disorder, panic disorder, and obsessive compulsive disorder), mood disorders (including depression, mania, bipolar disorders), trigeminal neuralgia, hearing loss, tinnitus, macular degeneration of the eye, emesis, brain edema, pain (including acute and chronic states, severe pain, intractable pain, neuropathic pain, and post-traumatic pain), tardive dyskinesia, sleep disorders (including narcolepsy), attention deficit/hyperactivity disorder, and conduct disorder.

In particular, the condition or disease is a central nervous system disorder selected from the group of anxiety disorders, psychotic disorders, personality disorders, substance-related disorders, eating disorders, mood disorders, migraine, epilepsy or convulsive disorders, childhood disorders, cognitive disorders, neurodegeneration, neurotoxicity and ischemia.

Preferably, the central nervous system disorder is an anxiety disorder, selected from the group of agoraphobia, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), panic disorder, posttraumatic stress disorder (PTSD), social phobia and other phobias.

Preferably, the central nervous system disorder is a psychotic disorder selected from the group of schizophrenia, delusional disorder, schizoaffective disorder, schizophreniform disorder and substance-induced psychotic disorder

Preferably, the central nervous system disorder is a personality disorder selected from the group of obsessive-compulsive personality disorder and schizoid, schizotypal disorder.

Preferably, the central nervous system disorder is a substance-related disorder selected from the group of alcohol abuse, alcohol dependence, alcohol withdrawal, alcohol withdrawal delirium, alcohol-induced psychotic disorder, amphetamine dependence, amphetamine withdrawal, cocaine dependence, cocaine withdrawal, nicotine dependence, nicotine withdrawal, opioid dependence and opioid withdrawal.

Preferably, the central nervous system disorder is an eating disorder selected from the group of anorexia nervosa and bulimia nervosa.

Preferably, the central nervous system disorder is a mood disorder selected from the group of bipolar disorders (I & II), cyclothymic disorder, depression, dysthymic disorder, major depressive disorder and substance-induced mood disorder.

Preferably, the central nervous system disorder is migraine.

Preferably, the central nervous system disorder is epilepsy or a convulsive disorder selected from the group of generalized nonconvulsive epilepsy, generalized convulsive epilepsy, petit mal status epilepticus, grand mal status epilepticus, partial epilepsy with or without impairment of consciousness, infantile spasms, epilepsy partialis continua, and other forms of epilepsy.

Preferably, the central nervous system disorder is attention-deficit/hyperactivity disorder.

Preferably, the central nervous system disorder is a cognitive disorder selected from the group of delirium, substance-induced persisting delirium, dementia, dementia due to HIV disease, dementia due to Huntington's disease, dementia due to Parkinson's disease, dementia of the Alzheimer's type, substance-induced persisting dementia and mild cognitive impairment.

Of the disorders mentioned above, the treatment of anxiety, schizophrenia, migraine, depression, and epilepsy are of particular importance.

At present, the fourth edition of the Diagnostic & Statistical Manual of Mental Disorders (DSM-IV) of the American Psychiatric Association provides a diagnostic tool for the identification of the disorders described herein. The person skilled in the art will recognize that alternative nomenclatures, nosologies, and classification systems for neurological and psychiatric disorders described herein exist, and that these evolve with medical and scientific progresses.

Because such positive allosteric modulators of mGluR2, including compounds of Formula (I), enhance the response of mGluR2 to glutamate, it is an advantage that the present methods utilize endogenous glutamate.

Because positive allosteric modulators of mGluR2, including compounds of Formula (I), enhance the response of mGluR2 to agonists, it is understood that the present invention extends to the treatment of neurological and psychiatric disorders associated with glutamate dysfunction by administering an effective amount of a positive allosteric modulator of mGluR2, including compounds of Formula (I), in combination with an mGluR2 agonist.

The compounds of the present invention may be utilized in combination with one or more other drugs in the treatment, prevention, control, amelioration, or reduction of risk of diseases or conditions for which compounds of Formula (I) or the other drugs may have utility, where the combination of the drugs together are safer or more effective than either drug alone.

Pharmaceutical Compositions

The invention also relates to a pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and, as active ingredient, a therapeutically effective amount of a compound according to the invention, in particular a compound according to Formula (I), a pharmaceutically acceptable salt thereof, a solvate thereof or a stereochemically isomeric form thereof.

The compounds according to the invention, in particular the compounds according to Formula (I), the pharmaceutically acceptable salts thereof, the solvates and the stereochemically isomeric forms thereof, or any subgroup or combination thereof may be formulated into various pharmaceutical forms for administration purposes. As appropriate compositions there may be cited all compositions usually employed for systemically administering drugs.

To prepare the pharmaceutical compositions of this invention, an effective amount of the particular compound, optionally in salt form, as the active ingredient is combined in intimate admixture with a pharmaceutically acceptable carrier or diluent, which carrier or diluent may take a wide variety of forms depending on the form of preparation desired for administration. These pharmaceutical compositions are desirable in unitary dosage form suitable, in particular, for administration orally, rectally, percutaneously, by parenteral injection or by inhalation. For example, in preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed such as, for example, water, glycols, oils, alcohols and the like in the case of oral liquid preparations such as, for example, suspensions, syrups, elixirs, emulsions and solutions; or solid carriers such as, for example, starches, sugars, kaolin, diluents, lubricants, binders, disintegrating agents and the like in the case of powders, pills, capsules and tablets. Because of the ease in administration, oral administration is preferred, and tablets and capsules represent the most advantageous oral dosage unit forms in which case solid pharmaceutical carriers are obviously employed. For parenteral compositions, the carrier will usually comprise sterile water, at least in large part, though other ingredients, for example, to aid solubility, may be included. Injectable solutions, for example, may be prepared in which the carrier comprises saline solution, glucose solution or a mixture of saline and glucose solution. Injectable suspensions may also be prepared in which case appropriate liquid carriers, suspending agents and the like may be employed. Also included are solid form preparations that are intended to be converted, shortly before use, to liquid form preparations. In the compositions suitable for percutaneous administration, the carrier optionally comprises a penetration enhancing agent and/or a suitable wetting agent, optionally combined with suitable additives of any nature in minor proportions, which additives do not introduce a significant deleterious effect on the skin. Said additives may facilitate the administration to the skin and/or may be helpful for preparing the desired compositions. These compositions may be administered in various ways, e.g., as a transdermal patch, as a spot-on, as an ointment.

It is especially advantageous to formulate the aforementioned pharmaceutical compositions in unit dosage form for ease of administration and uniformity of dosage. Unit dosage form as used herein refers to physically discrete units suitable as unitary dosages, each unit containing a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Examples of such unit dosage forms are tablets (including scored or coated tablets), capsules, pills, powder packets, wafers, suppositories, injectable solutions or suspensions and the like, and segregated multiples thereof.

The exact dosage and frequency of administration depends on the particular compound of formula (I) used, the particular condition being treated, the severity of the condition being treated, the age, weight, sex, extent of disorder and general physical condition of the particular patient as well as other medication the individual may be taking, as is well known to those skilled in the art. Furthermore, it is evident that said effective daily amount may be lowered or increased depending on the response of the treated subject and/or depending on the evaluation of the physician prescribing the compounds of the instant invention.

Depending on the mode of administration, the pharmaceutical composition will comprise from 0.05 to 99% by weight, preferably from 0.1 to 70% by weight, more preferably from 0.1 to 50% by weight of the active ingredient, and, from 1 to 99.95% by weight, preferably from 30 to 99.9% by weight, more preferably from 50 to 99.9% by weight of a pharmaceutically acceptable carrier, all percentages being based on the total weight of the composition.

As already mentioned, the invention also relates to a pharmaceutical composition comprising the compounds according to the invention and one or more other drugs in the treatment, prevention, control, amelioration, or reduction of risk of diseases or conditions for which compounds of Formula (I) or the other drugs may have utility as well as to the use of such a composition for the manufacture of a medicament. The present invention also relates to a combination of a compound according to the present invention and a mGluR2 orthosteric agonist. The present invention also relates to such a combination for use as a medicine. The present invention also relates to a product comprising (a) a compound according to the present invention, a pharmaceutically acceptable salt thereof or a solvate thereof, and (b) a mGluR2 orthosteric agonist, as a combined preparation for simultaneous, separate or sequential use in the treatment or prevention of a condition in a mammal, including a human, the treatment or prevention of which is affected or facilitated by the neuromodulatory effect of mGluR2 allosteric modulators, in particular positive mGluR2 allosteric modulators. The different drugs of such a combination or product may be combined in a single preparation together with pharmaceutically acceptable carriers or diluents, or they may each be present in a separate preparation together with pharmaceutically acceptable carriers or diluents.

The following examples are intended to illustrate but not to limit the scope of the present invention.

Chemistry

Several methods for preparing the compounds of this invention are illustrated in the following Examples. Unless otherwise noted, all starting materials were obtained from commercial suppliers and used without further purification.

Hereinafter, “THF” means tetrahydrofuran; “DMF” means N,N-dimethylformamide; “EtOAc” means ethyl acetate; “DCM” means dichloromethane; “DME” means 1,2-dimethoxyethane; “DCE” means 1,2-dichloroethane; “DIPE” means diisopropylether; “DMSO” means dimethylsulfoxide; “DBU” means 1,8-diaza-7-bicyclo[5.4.0]undecene;

Microwave assisted reactions were performed in a single-mode reactor: Initiator™ Sixty EXP microwave reactor (Biotage AB), or in a multimode reactor: MicroSYNTH Labstation (Milestone, Inc.).

Description 1 4-Benzyloxy-1-butyl-1H-pyridin-2-one (D1)

To a solution of 4-benzyloxy-JH-pyridin-2-one (5.0 g, 24.84 mmol) in acetonitrile (200 ml) were added 1-bromobutane (3.75 g, 27.33 mmol) and potassium carbonate (10.3 g, 74.52 mmol) and the mixture was heated at reflux for 16 hours. The reaction mixture was filtered through diatomaceous earth and concentrated in vacuo. The crude residue was then triturated with diethylether to yield pure D1 (6.26 g, 98%) as a white solid.

Description 2 1-Butyl-4-hydroxy-1H-pyridin-2-one (D2)

A mixture of intermediate D1 (2.01 g, 7.83 mmol) and a catalytic amount of 10% palladium on activated carbon in ethanol (300 ml) was stirred under a hydrogen atmosphere for two hours. The mixture was filtered through diatomaceous earth and the solvent was evaporated in vacuo to yield intermediate D2 (1.3 g, 100%) that was used without further purification.

Description 3 4-Bromo-1-butyl-1H-pyridin-2-one (D3)

To a solution of intermediate D2 (1.44 g, 8.6 mmol) in DMF (140 ml) was added phosphorus oxybromide (5.4 g, 18.9 mmol) and the mixture was heated at 110° C. for 1 hour. After cooling in an ice bath the solution was partitioned between water and EtOAc. After three extractions with EtOAc the combined organic fractions were dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude product was purified by column chromatography (silica gel; DCM as eluent). The desired fractions were collected and evaporated in vacuo to yield intermediate D3 (1.82 g, 93%).

Description 4 4-Bromo-1-(3-methylbutyl)-1H-pyridin-2-one (D4)

Intermediate D4 was prepared following the same procedure implemented for the synthesis of D3, using 4-hydroxy-1-(3-methylbutyl)-1H-pyridin-2-one as starting material, which was prepared by the same method used for the synthesis of intermediate D2, by reaction of 4-benzyloxy-1H-pyridin-2-one with 1-bromo-3-methylbutane.

Description 5 1-Butyl-3-chloro-4-hydroxy-M-pyridin-2-one (D5)

To a solution of intermediate D2 (2.0 g, 11.96 mmol) in DMF (30 ml) was added N-chlorosuccinimide (1.6 g, 11.96 mmol). The reaction was stirred at room temperature overnight and then it was concentrated in vacuo. The crude product was purified by column chromatography (silica gel; 0-5% methanol/DCM as eluent) to yield intermediate 05 (2.0 g, 83%).

Description 6 Trifluoro-methanesulfonic acid 1-butyl-3-chloro-2-oxo-1,2-dihydropyridin-4-yl ester (D6)

To a solution of intermediate D5 (2.0 g, 9.92 mmol) in DCM (80 ml) cooled at −78° C. was added pyridine (1.60 ml, 19.8 mmol). The resulting solution was stirred for 10 minutes after which trifloromethanesulfonic anhydride (1.90 ml, 10.9 mmol) was added, and the resulting solution was stirred at −78° C. for 3 hours. Then the mixture was warmed to room temperature and it was quenched by the addition of aqueous saturated ammonium chloride, it was diluted with water and extracted with DCM, dried (Na₂SO₄) and the solvent evaporated in vacuo, yielding intermediate D6 (3.31 g, 100%) as a crude that was used without further purification.

Description 7 (Tetrahydropyran-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-amine (D7)

A mixture of 4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenylamine (0.5 g, 2.28 mmol), tetrahydropyran-4-one (0.25 ml, 2.73 mmol) and sodium triacetoxy-borohydride (0.71 g, 3.42 mmol) in DCE (50 ml) was stirred at room temperature for 16 hours. The crude was filtered over diatomaceous earth, washed with DCM and the filtrate was evaporated in vacuo to yield D7 (0.69 g) that was used without further purification.

Description 8 1-(3-Methylbutyl)-4-[4-(tetrahydropyran-4-ylamino)-phenyl]-1H-pyridin-2-one (D8)

A suspension of intermediate D4 (0.46 g, 1.9 mmol), intermediate D7 (0.69 g, 2.28 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.21 g, 0.19 mmol) in a mixture of dioxane (4 ml) and saturated aqueous sodium carbonate (4 ml) was heated at 150° C. for 10 minutes, under microwave irradiation. The crude was filtered over diatomaceous earth and washed with EtOAc. The organic layer was separated and washed with brine, dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude product was purified by column chromatography (silica gel; DCM/EtOAc 8:2 and finally EtOAc as eluent). The desired fractions were collected and evaporated in vacuo to yield D8 (0.64 g, 95%) as a yellow solid.

Description 9 4-(4-Bromo-phenyl)-tetrahydropyran-4-carboxylic acid methyl ester (D9)

To a stirred solution of (4-bromophenyl)-acetic acid methylester (12.52 g, 54.6 mmol) and 15-crown-5 (1.2 g, 5.46 mmol) in DMF (100 ml) at room temperature was added NaH (60%) (4.74 g, 119 mmol) portionwise. After stirring at room temperature for 40 minutes, NaI (8.14 g, 54.6 mmol) and 2-chloroethyl ether (13.76 g, 96.2 mmol) were added. The reaction mixture was stirred at room temperature for 10 hours, after which the solvent was evaporated in vacuo. The residue was treated with a mixture of EtOAc and toluene (1:1) and washed with a solution of 0.5 N HCl. The aqueous layer was further extracted with more EtOAc/toluene (1:1) and the combined organic extracts were washed with water, then with an aqueous saturated solution of NaHCO₃ and finally with brine. The combined organic extracts were dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude residue was triturated with n-heptane and the soluble fraction was evaporated to dryness under reduced pressure to yield D9 (3.96 g, 24%) as a yellow liquid.

Description 10 [4-(4-Bromophenyl)-tetrahydropyran-4-yl]-methanol (D10)

To a solution of intermediate D9 (1.07 g, 3.58 mmol) in THF (20 ml) stirred at −10° C. under N₂ atmosphere, was added a 1.0 M solution of lithium aluminum hydride in THF dropwise (3.58 ml, 3.58 mmol). The resulting solution was gradually warmed to room temperature and further stirred for 2 hours. After cooling to 0° C. an aqueous 10% NaOH solution was carefully added and the resulting mixture was allowed to reach room temperature. Then it was extracted with DCM, dried (Na₂SO₄) and the solvent evaporated in vacuo to yield intermediate D10 (0.96 g, 99%) as a white solid that was used without further purification.

Description 11 {4-[4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-tetrahydropyran-4-yl}-methanol (D11)

To a solution of intermediate D10 (0.96 g, 3.53 mmol) in dioxane (12 ml) and DMF (3 ml) were added bis(pinacolato)diboron (1.43 g, 5.65 mmol) and potassium acetate (1.04 g, 10.59 mmol). The mixture was degassed and then [1,1′-bis(diphenylphosphino)-ferrocene]-dichloropalladium(II)— complex with DCM (1:1) (0.09 g, 0.106 mmol) was added. The reaction mixture was heated at 150° C. for 40 minutes under microwave irradiation. After cooling to room temperature water was added and the mixture was extracted with EtOAc. The organic fraction was dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude residue was purified by column chromatography (silica gel; DCM as eluent). The desired fractions were collected and evaporated in vacuo to afford an oily residue that was triturated with n-heptane to yield D11 (0.65 g, 58%) as a white solid.

Description 12 4-(Tetrahydropyran-2-yloxymethyl)-4-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-tetrahydropyran (D12)

A mixture of intermediate D11 (0.58 g, 1.8 mmol), 3,4-dihydro-2H-pyran (0.2 ml, 2.18 mmol) and p-toluenesulfonic acid (catalytic amount) in dry DCM (20 ml) was stirred at room temperature for 1 hour. The reaction mixture was then washed with an aqueous saturated solution of NaHCO₃, the combined organic extracts were dried (Na₂SO₄) and the solvent was evaporated in vacuo. The crude residue was purified by column chromatography (silica gel; DCM as eluent). The desired fractions were collected and evaporated in vacuo to yield D12 (0.73 g, 100%) that was used without further purification.

EXAMPLE 1 3-Chloro-1-(3-methylbutyl)-4-[4-(tetrahydropyran-4-ylamino)-phenyl]-1H-pyridin-2-one (E1)

A solution of intermediate D8 (0.65 g, 1.91 mmol) and N-chlorosuccinimide (0.25 g, 1.91 mmol) in DMF (10 ml) was stirred at 45° C. for 16 hours. After cooling to room temperature water was added and the solution was extracted with EtOAc, The organic layer was separated and washed with brine, dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude product was purified by column chromatography (silica gel; DCM/EtOAc 8:2 as eluent). The desired fractions were collected and evaporated in vacuo to yield E1 (0.20 g, 28%) as a pale pink solid.

Melting point: >300° C.

EXAMPLE 2 1-Butyl-3-chloro-4-{4-[4-(tetrahydropyran-2-yloxymethyl)-tetrahydropyran-4-yl]-phenyl}-1H-pyridin-2-one (E2)

A mixture of intermediate D6 (0.17 g, 0.5 mmol), intermediate D12 (0.2 g, 0.5 mmol), catalyst tetrakis(triphenylphosphine)palladium(0) (0.03 g, 0.025 mmol) and NaHCO₃ (3 g, excess) in dioxane (6 ml) was heated at 150° C. for 10 minutes under microwave irradiation. After cooling to room temperature the reaction mixture was filtered through diatomaceous earth, treated with EtOAc and the organic layer was washed with water and then with brine. The organic fraction was dried (Na₂SO₄) and the solvent evaporated in vacuo. The crude residue was purified by column chromatography (silica gel; 0-10% EtOAc/DCM as eluent). The desired fractions were collected and evaporated in vacuo to yield E2 (0.10 g, 45%) as a colorless oil.

EXAMPLE 3 1-Butyl-3-chloro-4-[4-(4-hydroxymethyl-tetrahydropyran-4-yl)-phenyl]-1H-pyridin-2-one (E3)

A mixture of compound E2 (0.10 g, 0.22 mmol) and a catalytic amount of p-toluenesulfonic acid in methanol (10 ml) was stirred at room temperature for 1 hour. The solvent was evaporated in vacuo and the resulting residue was taken up with DCM, washed with an aqueous saturated solution of NaHCO₃, the combined organic extracts were dried (Na₂SO₄) and the solvent was evaporated in vacuo. The crude residue was purified by column chromatography (silica gel; 0-30% EtOAc/DCM as eluent). The desired fractions were collected and evaporated in vacuo to yield E3 (0.05 g, 61%) as a colourless oil. Compounds E4 to E9 (Table 1) were prepared in a similar manner. Physico-Chemical Data LCMS—General Procedure

The HPLC measurement was performed using a HP 1100 from Agilent Technologies comprising a pump (quaternary or binary) with degasser, an autosampler, a column oven, a diode-array detector (DAD) and a column as specified in the respective methods below. Flow from the column was split to a MS spectrometer. The MS detector was configured with an electrospray ionization source. Nitrogen was used as the nebulizer gas. The source temperature was maintained at 140° C. Data acquisition was performed with MassLynx-Openlynx software.

In addition to the general procedure: Reversed phase HPLC was carried out on an XDB-C18 cartridge (1.8 μm, 2.1×30 mm) from Agilent, with a flow rate of 1 ml/min, at 60° C. The gradient conditions used are: 90% A (0.5 g/l ammonium acetate solution), 5% B (acetonitrile), 5% C (methanol) to 50% B and 50% C in 6.5 minutes, to 100% B at 7 minutes and equilibrated to initial conditions at 7.5 minutes until 9.0 minutes. Injection volume 2 μl. High-resolution mass spectra (Time of Flight, TOF) were acquired only in positive ionization mode by scanning from 100 to 750 in 0.5 seconds using a dwell time of 0.1 seconds. The capillary needle voltage was 2.5 kV and the cone voltage was 20 V. Leucine-Enkephaline was the standard substance used for the lock mass calibration.

Melting Points

For a number of compounds, melting points were determined in open capillary tubes on a Mettler FP62 apparatus. Melting points were measured with a temperature gradient of 3 or 10° C./minute. Maximum temperature was 300° C. The melting point was read from a digital display and were obtained with experimental uncertainties that are commonly associated with this analytical method.

Table 1 lists compounds of Formula (I) that were prepared according to one of the above Examples (Ex. no.).

TABLE 1

Melting Point M. Wt RT Ex. R1 R3 R4 X Y (° C.) Free base MH+ (min) E1

H H NH O decomposes 374 375 4.28 E2

H

bond O n.d. n.d. n.d. n.d. E3

H —CH₂OH bond O n.d. 375 376 3.34 E4

3′-Cl H O O 154 407 408 4.59 E5

3′-CF₃ H NH O 173 426 427 4.49 E6

3′-Cl H NH O 231 392 393 4.15 E7

3′-Cl H NH C(CH₃)OH 227.4 422 423 4.73 E8

H H NH CHOH (cis) 186.2 374 375 3.95 E9

H H NH CHOH (trans) 263.5 374 375 3.62 n.d.: not determined

D. Pharmacological Examples

The compounds provided in the present invention are positive allosteric modulators of mGluR2. These compounds appear to potentiate' glutamate responses by binding to an allosteric site other than the glutamate binding site. The response of mGluR2 to a concentration of glutamate is increased when compounds of Formula (I) are present. Compounds of Formula (I) are expected to have their effect substantially at mGluR2 by virtue of their ability to enhance the function of the receptor. The behaviour of positive allosteric modulators tested at mGluR2 using the [³⁵S]GTPγS binding assay method described below and which is suitable for the identification of such compounds, and more particularly the compounds according to Formula (I), are shown in Table 4.

[³⁵S]GTPγS Binding Assay

The [³⁵S]GTPγS binding assay is a functional membrane-based assay used to study G-protein coupled receptor (GPCR) function whereby incorporation of a non-hydrolysable form of GTP, [³⁵S]GTPγS (guanosine 5′-triphosphate, labelled with gamma-emitting ³⁵S), is measured. The G-protein α subunit catalyzes the exchange of guanosine 5′-diphosphate (GDP) by guanosine triphosphate (GTP) and on activation of the GPCR by an agonist, [³⁵S]GTPγS, becomes incorporated and cannot be cleaved to continue the exchange cycle (Harper (1998) Current Protocols in Pharmacology 2.6.1-10, John Wiley & Sons, Inc.). The amount of radioactive [³⁵S]GTPγS incorporation is a direct measure of the activity of the G-protein and hence the activity of the agonist can be determined. mGluR2 receptors are shown to be preferentially coupled to Gαi-protein, a preferential coupling for this method, and hence it is widely used to study receptor activation of mGluR2 receptors both in recombinant cell lines and in tissues (Schaffhauser et al 2003, Pinkerton et al, 2004, Mutel et al (1998) Journal of Neurochemistry. 71:2558-64; Schaffhauser et al (1998) Molecular Pharmacology 53:228-33). Here we describe the use of the [³⁵S]GTPγS binding assay using membranes from cells transfected with the human mGluR2 receptor and adapted from Schaffhauser et al ((2003) Molecular Pharmacology 4:798-810) for the detection of the positive allosteric modulation (PAM) properties of the compounds of this invention.

Membrane Preparation

CHO-cells were cultured to pre-confluence and stimulated with 5 mM butyrate for 24 hours, prior to washing in PBS, and then collection by scraping in homogenisation buffer (50 mM Tris-HCl buffer, pH 7.4, 4° C.). Cell lysates were homogenized briefly (15 s) using an ultra-turrax homogenizer. The homogenate was centrifuged at 23 500×g for 10 minutes and the supernatant discarded. The pellet was resuspended in 5 mM Tris-HCl, pH 7.4 and centrifuged again (30 000×g, 20 min, 4° C.). The final pellet was resuspended in 50 mM HEPES, pH 7.4 and stored at −80° C. in appropriate aliquots before use. Protein concentration was determined by the Bradford method (Bio-Rad, USA) with bovine serum albumin as standard.

[³⁵S]GTPγS Binding Assay

Measurement of mGluR2 positive allosteric modulatory activity of test compounds in membranes containing human mGluR2 was performed using frozen membranes that were thawed and briefly homogenised prior to pre-incubation in 96-well microplates (15 μg/assay well, 30 minutes, 30° C.) in assay buffer (50 mM HEPES pH 7.4, 100 mM NaCl, 3 mM MgCl₂, 50 μM GDP, 10 μg/ml saponin,) with increasing concentrations of positive allosteric modulator (from 0.3 nM to 50 μM) and either a minimal pre-determined concentration of glutamate (PAM assay), or no added glutamate. For the PAM assay, membranes were pre-incubated with glutamate at EC₂₅ concentration, i.e. a concentration that gives 25% of the maximal response glutamate, and is in accordance to published data (Pin et al. (1999) Eur. J. Pharmacol. 375:277-294). After addition of [³⁵S]GTPγS (0.1 nM, f.c.) to achieve a total reaction volume of 200 microplates were shaken briefly and further incubated to allow [³⁵S]GTPγS incorporation on activation (30 minutes, 30° C.). The reaction was stopped by rapid vacuum filtration over glass-fibre filter plates (Unifilter 96-well GF/B filter plates, Perkin-Elmer, Downers Grove, USA) microplate using a 96-well plate cell harvester (Filtermate, Perkin-Elmer, USA), and then by washing three times with 300 μl of ice-cold wash buffer (Na₂PO₄.2H₂0 10 mM, NaH₂PO₄.H₂0 10 mM, pH=7.4). Filters were then air-dried, and 40 μl of liquid scintillation cocktail (Microscint-O) was added to each well, and membrane-bound [³⁵S]GTPγS was measured in a 96-well scintillation plate reader (Top-Count, Perkin-Elmer, USA). Non-specific [³⁵S]GTPγS binding is determined in the presence of cold 10 μM GTP. Each curve was performed at least once using duplicate sample per data point and at 11 concentrations.

Data Analysis

The concentration-response curves of representative compounds of the present invention in the presence of added EC₂₅ of mGluR2 agonist glutamate to determine positive allosteric modulation (PAM), were generated using the Prism GraphPad software (Graph Pad Inc, San Diego, USA). The curves were fitted to a four-parameter logistic equation (Y=Bottom+(Top-Bottom)/(1+10^((LogEC₅₀-X)*Hill Slope) allowing determination of EC₅₀ values. The EC₅₀ is the concentration of a compound that causes a half-maximal potentiation of the glutamate response. This is calculated by subtracting the maximal responses of glutamate in presence of a fully saturating concentration of a positive allosteric modulator from the response of glutamate in absence of a positive allosteric modulator. The concentration producing the half-maximal effect is then calculated as EC₅₀.

TABLE 2 Pharmacological data for compounds according to the invention. All compounds were tested in presence of mGluR2 agonist, glutamate at a predetermined EC₂₅ concentration, to determine positive allosteric modulation (GTPγS-PAM). Values shown are averages of duplicate values of 11-concentration response curves, from at least one experiment. All tested compounds showed a pEC₅₀ (−logEC₅₀) value of more than 5.0, from 6.09 to 7.40. The error of determination of a pEC₅₀ value for a single experiment is estimated to be about 0.3 log-units. GTPgS - hR2 PAM Comp. No. pEC₅₀ 1 n.d. 2 n.d. 3 n.d. 4 6.56 5 6.09 6 6.24 7 7.40 8 n.d. 9 n.d. n.d. = not determined

E. Composition Examples

“Active ingredient” as used throughout these examples relates to a final compound of formula (I), the pharmaceutically acceptable salts thereof, the solvates and the stereochemically isomeric forms thereof.

Typical examples of recipes for the formulation of the invention are as follows:

1. Tablets

Active ingredient 5 to 50 mg Di-calcium phosphate 20 mg Lactose 30 mg Talcum 10 mg Magnesium stearate 5 mg Potato starch ad 200 mg

In this Example, active ingredient can be replaced with the same amount of any of the compounds according to the present invention, in particular by the same amount of any of the exemplified compounds.

2. Suspension

An aqueous suspension is prepared for oral administration so that each 1 milliliter contains 1 to 5 mg of one of the active compounds, 50 mg of sodium carboxymethyl cellulose, 1 mg of sodium benzoate, 500 mg of sorbitol and water ad 1 ml.

3. Injectable

A parenteral composition is prepared by stirring 1.5% by weight of active ingredient of the invention in 10% by volume propylene glycol in water.

4. Ointment

Active ingredient 5 to 1000 mg Stearyl alcohol 3 g Lanoline 5 g White petroleum 15 g Water ad 100 g

In this Example, active ingredient can be replaced with the same amount of any of the compounds according to the present invention, in particular by the same amount of any of the exemplified compounds.

Reasonable variations are not to be regarded as a departure from the scope of the invention. It will be obvious that the thus described invention may be varied in many ways by those skilled in the art. 

The invention claimed is:
 1. A compound having the formula (I)

or a stereochemically isomeric form thereof, wherein R¹ is C₁₋₆alkyl; or C₁₋₃ alkyl substituted with C₃₋₇cycloalkyl, phenyl, or phenyl substituted with halo, trifluoromethyl or trifluoromethoxy; R² is halo, trifluoromethyl, C₁₋₃ alkyl or cyclopropyl; R³ is hydrogen, halo or trifluoromethyl; R⁴ is hydrogen, C₁₋₃alkyl, C₁₋₃alkyloxy, hydroxyC₁₋₃alkyl or tetrahydropyran-2-yloxy C₁₋₃alkyl; n is 1 or 2; X is a covalent bond, O or NR⁵; R⁵ is hydrogen, C₁₋₃alkyl or hydroxyC₂₋₃alkyl; Y is O or CR⁶(OH); R⁶ is hydrogen or C₁₋₃alkyl; or R⁴ and R⁶ form a radical —CH₂—CH₂—;or a pharmaceutically acceptable salt thereof.
 2. The compound according to claim 1 wherein R¹is 1-butyl, 2-methyl-1-propyl, 3-methyl-1-butyl, (cyclopropyl)methyl or 2-(cyclopropyl)- 1-ethyl; R² is halo; R³ is hydrogen, chloro or trifluoromethyl; R⁴ is hydrogen or hydroxymethyl; N is 2; X is a covalent bond, O or NR⁵; R⁵ is hydrogen; Y is O or CR⁶(OH); R⁶ is hydrogen or methyl; or a pharmaceutically acceptable salt thereof.
 3. The compound according to claim 1 wherein R¹ is 1-butyl, 3-methyl-1-butyl, (cyclopropyl)methyl or 2-(cyclopropyl)-1-ethyl; R² is chloro; R³ is hydrogen or chloro; R⁴ is hydrogen or hydroxymethyl; n is 2; X is a covalent bond, O or NR⁵; R⁵ is hydrogen; Y is O or CR⁶(OH); R⁶ is hydrogen or methyl; or a pharmaceutically acceptable salt thereof.
 4. A compound wherein said compound is trifluoro-methanesulfonic acid 1-butyl-3-chloro-2-oxo-1,2-dihydropyridin-4-yl ester.
 5. A pharmaceutical composition comprising a therapeutically effective amount of a compound according to claim 1 and a pharmaceutically acceptable carrier or excipient. 